Twivine has defeated her former friends with the black vines and their Elements of Harmony. The five ponies became helpless and captured by the vines and Twivine used the Dark Tree of Harmony's power to turn them evil. Together, they became… The Plundering Six.
"Plunder Pie - The Element of Wicked Laughter"
She is the dastardly of the six ponies and her main weapon is the Party Plunderball Cannon. It shoots out black spiked balls that are very similar to the Spinys from Super Mario Bros. Also she gives out dark presents that have plunder vines in them, ready to capture her victims.
"Flutterthorn - The Element of Cruelty"
Much like the corrupted Fluttershy from "The Return of Harmony", she is willing to make everypony suffer in a torturing matter. Not even Angel Bunny can resist from Flutterthorn.
"Rainbow Briar - The Element of Treachery"
Rainbow Briar is the toughest of the Plundering Six and she can defeat her opponents in a matter of minutes. Her speed and power is much greater than an average Rainbow Dash. She can also perform her Double Rainboom, which it can take out an enormous area, like Ponyville. She only does this when Twivine gives her an order to do it.
"Rarivine - The Element of Grudge"
She is the poison ivy of the Plundering Six just like Twivine, and she is willing to use dark plunder crystals to hurl at her victims. She can cause a unicorn's magic spell to go haywire by casting a particular spell that the plunder vines have.
"Appleplant - Element of Dishonesty"
Appleplant is Twivine's assistant just like Dark Vine Cadenza. She gives her victims a dark apple that will poison them for a short period of time. She uses her lasso made of vine to capture her enemies as well.